This invention generally relates to a rapid exchange type dilatation catheter system which is suitable for intravascular procedures such as percutaneous transluminal coronary angioplasty (PTCA) and which allows for the exchange of the guidewire during such procedures without loss of access to the patient's arterial location.
In PTCA procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced into the cardiovascular system of a patient and advanced therein until the preshaped distal tip thereof is disposed within the aorta adjacent to the ostium of the desired coronary artery. The guiding catheter is twisted or torqued from the proximal end to turn the distal tip of the guiding catheter so that it can be guided into the coronary ostium. A dilatation catheter having a balloon on the distal end thereof and a guidewire slidably disposed within an inner lumen of the thereof and a guidewire slidably disposed within an inner lumen of the dilatation catheter are introduced into and advanced through the guiding catheter to the distal tip thereof. The distal tip of the guidewire is usually manually shaped (i.e. curved) by the physician or one of the attendants before the guidewire is introduced into the guiding catheter along with the dilatation catheter. The guidewire is first advanced out the distal tip of the guiding catheter, which is seated in the ostium of the patient's coronary artery, into the patient's coronary artery. A torque is applied to the proximal end of the guidewire, which extends out of the patient, to guide the curved or otherwise shaped distal end of the guidewire as the guidewire is advanced within the coronary anatomy until the shaped distal end of the guidewire enters the desired artery. The advancement of the guidewire within the selected artery continues until it crosses the lesion to be dilated. The dilatation catheter is then advanced out of the distal tip of the guiding catheter, over the previously advanced guidewire, until the balloon on the distal extremity of the dilatation catheter is properly positioned across the lesion. Once properly positioned, the flexible, relatively inelastic balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., 4-12 atmospheres) to dilate the stenosed region of the diseased artery. The balloon is then deflated so that the dilatation catheter can be removed from the dilated stenosis and blood flow can then be resumed therethrough.
A rapid exchange type dilatation catheter has a short guidewire-receiving sleeve or inner lumen extending a short distance through just the distal portion of the catheter shaft. The sleeve or inner lumen preferably extends proximally at least about 10 cm, typically about 25 cm, from a first guidewire port in the distal end of the catheter to a second guidewire port. A slit may be provided in the catheter wall defining the first guidewire receiving lumen which extends proximally from a location proximal to the inflatable balloon to the second guidewire port to facilitate the separation of the catheter from the guidewire. The catheter is advanced within the patient's vascular system with the guidewire disposed within the guidewire receiving inner lumen in the distal section of the catheter shaft in a conventional fashion. Alternatively, the guidewire may be first advanced within the patient's vasculature until the distal end of the guidewire extends distally to the stenosis to be dilated and then the catheter is mounted onto the proximal end of the in-place guidewire and then advanced over the guidewire until the dilatation balloon is properly disposed across the stenosis. The structure of the catheter allows for the rapid exchange of the catheter without the need for an exchange wire or adding a guidewire extension to the proximal end of the guidewire.
Rapid exchange type catheters are available from the licensee of the present invention, Advanced Cardiovascular Systems, Inc., under the trademark ACS RX.RTM. which are basically described and claimed in U.S. Pat. No. 5,061,273 (Yock) and U.S. Pat. No. 4,748,982 (Horzewski et al.). The catheter design embodying the Yock and Horzewski et al. improvements has been widely praised by members of the medical profession and it has met with much commercial success in the market place. Nonetheless, there are some inconveniences in its use because the catheter does not allow for the exchange or replacement of the guidewire. For example, the shaped distal tip of the guidewire may become deformed in use or the shape of the distal tip or the size of the guidewire may be found to be no longer suitable for the particular procedure within the patient's vasculature. In this instance the physician might want to remove the guidewire and reshape the distal tip or replace the first guidewire with another having the desired size, stiffness or shape. However, when the guidewire in a dilatation catheter system embodying the Yock and Horzewski et al. improvements is removed, access to the desired arterial location through the distal guidewire lumen of the catheter is lost. Unfortunately, there is no way to clinically determine before the guidewire is inserted into the patient in an angioplasty procedure whether a guidewire or a catheter will have to be exchanged during the procedure.
What has been needed and heretofore unavailable is an easily usable intravascular catheter system which allows for the rapid exchange of either the catheter or the guidewire during an intravascular procedure without losing access to the desired region of the patient's arterial system. The present invention satisfies this and other needs.